For certain applications, it is desirable to have multiple lights flash in synchronization. For example, on an aircraft, it is desirable to have the anti-collision lights aircraft flash at the same time for purposes of safety and aesthetics. In an aircraft's anti-collision lighting system, each lighthead typically has a power supply that connects to the aircraft's 115 V/400 Hz bus. By using a common AC bus as a timing reference, the anti-collision lights automatically flash together. For this reason, the flash rate is directly proportional to the aircraft's generator frequency, which is usually well controlled.
Recently, however, aircraft have been introduced with wild frequency power where the AC frequency can be anywhere between 360 and 800 Hz. Because a flash rate variation of 220% is unacceptable, some means of synchronization is required.
One existing solution for synchronization, often used for aircraft whose anti-collision lights are powered by a 28 VDC system, is for each power supply to provide its own timing and “sync” signal. In such systems, a sync wire connects all of the lighting units, allowing the fastest unit to signal the others when to flash.
A wireless version of this existing solution uses a high-frequency “carrier” signal on the AC line as the sync signal. This requires a carrier send/receive circuit in each lighting unit and a single filter unit to keep the carrier off the aircraft's main AC bus.
Another existing alternative is to connect each of the lighting units to a dedicated synchronization controller. This solution is available if single-point-failure is tolerable, and rewiring of the aircraft is allowed.
However, it would be advantageous to dispose of any requirement of installing synchronization wires, injecting synchronization signals onto an AC bus, or installing a separate filter or controller unit. This would simplify the synchronization of flashing lights, such as anti-collision lights, which are powered by a wild frequency source.